In the present work, ZnO nanorods array were successfully grown on ITO substrate via chemical bath deposition method (CBD). The seeding solution was prepared at low temperature (0°C) using zinc nitrate tetrahydrate and hexamethylenetetramine. The as-deposited ZnO nanorods were hexagonal wurtzite structure growing vertically on the substrate. Various reaction times from 3 to 5 hours were applied upon the CBD process at 90°C. The results showed that the duration of reaction time has affected the nanorods array properties. With the increase of reaction time from 3 to 5 hours has increased the diameter and crystallite size of nanorods from 325 to 583 nm, and from 22.68 to 34.28 nm. As a result, the band gap energy, Eg of ZnO nanorods decreased from 3.63 to 3.13 eV.